Thêm cognostics tùy chỉnh

library(ggplot2)
library(dplyr)
library(gapminder)
library(trelliscopejs)
space_to_dash <- function(x) gsub(" ", "-", x)

# Group by country and create the two new variables
gap <- gapminder %>%
  group_by(___) %>%
  mutate(
    delta_lifeExp = tail(___, 1) - head(___, 1),
    ihme_link = paste0("http://www.healthdata.org/", space_to_dash(___)))

# Add the description
gap$delta_lifeExp <- cog(gap$delta_lifeExp, desc = "___")
# Specify the default label
gap$ihme_link <- cog(gap$ihme_link, default_label = ___)

ggplot(gap, aes(year, lifeExp)) +
  geom_point() +
  facet_trelliscope(~ country + continent,
    name = "lifeExp_by_country",
    desc = "Life expectancy vs. year.",
    nrow = 1, ncol = 2,
    scales = c("same", "sliced"))